A method and apparatus, the method comprising: forming a layer of two dimensional material (23), in particular graphene, on a first release layer; forming, possibly a (gate) insulating layer (35), and at least two, preferably three, electrodes (25); forming a second release layer overlaying at least a portion of the layer of two dimensional material; providing mouldable polymer (24, 26, 28) overlaying the at least two electrodes and the second release layer; and removing the first and second release layers to provide a cavity (29) between the mouldable polymer (26) and the layer of two dimensional material (23).